The present invention relates to heat transfer element baskets and, more specifically, to an assembly of heat absorbent plates in a basket for use in a heat exchanger wherein heat is transferred by means of the plates from a hot heat exchange fluid to a cold heat exchange fluid. The present invention has particular application in heat transfer apparatus of the rotary regenerative type wherein the heat transfer element is heated by contact with a hot gaseous heat exchange fluid and thereafter brought in contact with a cool gaseous heat exchange fluid to which the heat transfer element gives up its heat.
One type of heat exchange apparatus commonly used for gas-to-gas heat exchange in the process industry and for gas-to-air heat exchange on utility steam generators is the well-known rotary regenerative heat exchanger. Typically, a rotary. regenerative heat exchanger has a cylindrical rotor divided into compartments in which are disposed a mass of heat transfer element which, as the rotor turns, is alternately exposed to a stream of heating gas and then upon rotation of the rotor to a stream of cooler air or other gaseous fluid to be heated. The heat absorbent mass typically comprises a plurality of heat transfer element basket assemblies mounted in sector shaped compartments. Each of the heat transfer element basket assemblies houses a plurality o heat transfer plates which when exposed to the heating gas absorb heat therefrom and then when exposed to the cool air or other gaseous fluid to be heated, the heat absorbed from the heating gas by the heat transfer plates is transferred to the cooler gas.
Typically, such an element basket assembly comprises a pair of spaced end plates held together by paired side straps interconnecting the end plates along the sides thereof. A plurality of heat transfer plates are stacked in closely spaced relationship within the basket housing to provide a plurality of passageways between adjacent plates through which the heat exchange fluids pass. One or more retaining bars are welded between the end plates across the top and bottom ends thereof to prevent the heat transfer element plates from falling out of the open ends of the element basket. The side straps which interconnect the spaced end plates extend in pairs along the opposite sides of the stacked array of heat exchange elements. On each side of the heat exchange element is a first side strap extending between the upper regions of the spaced end plates and a second side strap extending between the lower region of the end plates in spaced, parallel relationship to the first side strap.
Although such basket assemblies are commonly used, a problem sometimes arises when two basket assemblies of this type are disposed side-by-side and is a sector compartment of a heat exchanger. It is not unusual for the side straps to bow after a period of time in the heat exchanger due to the influence of the hot gases flowing through the element baskets. When the side straps have bowed, it is often difficult to remove the element baskets from the sector compartments of the heat exchanger as the bowed side straps will hang up on side straps of adjacent baskets as the element basket is pulled out of the heat exchanger. As the heat exchange element deteriorates during normal operation, it is necessary to periodically replace all of the elements within the heat exchanger.
It is, therefore, an object of the present invention to provide an improved element basket assembly designed to preclude the hangup of element baskets during removal due to the bowing of the side straps.